Tesla Model S waffling

[lemming]

Originally Posted by JST

I don't think that's fair. My experience on TMC is that Tesla owners show a near universal concern for how their power is generated; many have installed solar panels to offset the power their car draws.

I think you have to assume that as a baseline. People over there know that we should dump coal in the same way that people here know that manuals are better. You don't have to say it every time.

okay, i'll accept that. i only read the last two posts (at the time you posted the link) and I found them to be loathsome, but they're probably the two a$$holes out 500 Tesla posters.

[ZBB]

Originally Posted by JST

I don't think that's fair. My experience on TMC is that Tesla owners show a near universal concern for how their power is generated; many have installed solar panels to offset the power their car draws.

I think you have to assume that as a baseline. People over there know that we should dump coal in the same way that people here know that manuals are better. You don't have to say it every time.

This is my observation also. Tesla owners with solar (which is a very high percent of the TMC members...) are very proud that they run their cars on sunlight.

As for me, my car is 40% coal powered and 38% nuclear powered -- but only because I'm on the grid and that's AZ's mix. Unfortunately, our house isn't oriented for optimal solar panel utilization and if we went solar, we could only replace ~70% of our pre-Tesla energy use from Solar (we looked at it about 2 years ago) -- at that rate, the math didn't make sense to go solar (would have saved at most $40/month -- so had a really long payback of the up-front cost). Our neighbors have the same roof layout as us, but rotated 180 degrees -- and their solar gives them about 90% replacement, which saves them over $100/month. Now that I use 400-500 kWh per month for the Tesla, the math would be even worse -- although solar panels have gotten a bit more efficient, so at some point we'll need to look again...

[John V]

Solar panels are, and have always been, a poor investment. They really exist only to make people feel better about themselves.

There are ways to get power from the sun (and I'm not including photosynthesis related power here, i.e. growing plants that can be converted into fuel) and solar panels aren't it.

[lemming]

Originally Posted by John V

Solar panels are, and have always been, a poor investment. They really exist only to make people feel better about themselves.

There are ways to get power from the sun (and I'm not including photosynthesis related power here, i.e. growing plants that can be converted into fuel) and solar panels aren't it.

what is the max efficiency of consumer-grade solar panels, anyway?

to guess, therefore, you're talking about 'mirror' farms which direct and focus the heat of sunlight to boil a liquid substance to drive generators?

[John V]

Originally Posted by lemming

what is the max efficiency of consumer-grade solar panels, anyway?

to guess, therefore, you're talking about 'mirror' farms which direct and focus the heat of sunlight to boil a liquid substance to drive generators?

There are several factors. What you're really concerned with is watts per square meter, and it's laughably bad, and the payback period. I don't know if it's still true, but it used to be that the cheapest solar cells had the shortest payback period despite having half the energy conversion efficiency of the multi-junction stuff.

Yes, the focused mirror farms is what I was getting at. Of course, they're not that practical to build on a small scale, and they require a lot of maintenance.

[JST]

Originally Posted by lemming

what is the max efficiency of consumer-grade solar panels, anyway?

to guess, therefore, you're talking about 'mirror' farms which direct and focus the heat of sunlight to boil a liquid substance to drive generators?

http://cleantechnica.com/2014/02/02/...ost-efficient/

http://www.forbes.com/sites/quora/20...o-inefficient/

[lemming]

Originally Posted by JST

http://cleantechnica.com/2014/02/02/...ost-efficient/



http://www.forbes.com/sites/quora/20...o-inefficient/

Well....it could be worse. The internal combustion engine is 33%?

Now I'm curious about geothermal and hydroelectric power. Given the constraints here for solar, it's not tenable and actually laughable unless people are using these units to heat water.

[JST]

Why does the efficiency matter? Sunlight is literally free and inexhaustible. If your input costs zero, any efficiency above zero is fine.

More meaningful, of course, is the amount of power generated per square meter (since you have a finite amount of land to build on) and the amount the panel costs to build in the first place. But neither of those measures are captured in the overall efficiency figure.

[John V]

Originally Posted by JST

Why does the efficiency matter? Sunlight is literally free and inexhaustible. If your input costs zero, any efficiency above zero is fine.

More meaningful, of course, is the amount of power generated per square meter (since you have a finite amount of land to build on) and the amount the panel costs to build in the first place. But neither of those measures are captured in the overall efficiency figure.

Repost.

[lemming]

Originally Posted by JST

Why does the efficiency matter? Sunlight is literally free and inexhaustible. If your input costs zero, any efficiency above zero is fine.

More meaningful, of course, is the amount of power generated per square meter (since you have a finite amount of land to build on) and the amount the panel costs to build in the first place. But neither of those measures are captured in the overall efficiency figure.

i think it matters because most houses have a limited footprint to use for solar panels to create a single cell.

and I guess I'd need to understand how useful 21% efficiency is over a small footprint. what does that do really? charge a 12V battery? 2 or 3? I really don't know, but given that Teslas and the like require 220V lines to charge at a useful rate, i'm dubious as to what solar panels are doing relative to the needs of a car like the Volt or even the Tesla.

it's like using 1000 Brita carafes to cleanse a body of water the size Golden Pond so it's drinkable for Haiti during a cholera outbreak. noble idea. odds don't seem to favor practicality.